在 C# 中的组合框或列表控件中放置水平线 [英] putting horizontal line in a combo box or list control in C#

问题描述

回答链接:(我可以在组合框或列表控件中放置一条水平线吗?)

我已经在 C# (VS 2010) Windows 窗体中创建了一个代码，但它需要改进.项目前的符号-"在项目后呈现一行.

I've create a code in C# (VS 2010) Windows Forms but it needs improvement. The symbol "-" in front of the item renders a line after the item.

我在组合项集合中的输入如下:

My inputs in the combo item collections are as follow:

-All Names
Henry (Father)
-Nancy (Mother)
Sapphire
Vincent

我的组合显示如下:

All Names
------------------
Henry (Father)
Nancy (Mother)
------------------
Sapphire
Vincent

虽然我的代码是:

    public Form1()
    {
        InitializeComponent();
        comboBox1.DrawMode = DrawMode.OwnerDrawFixed;
        comboBox1.DrawItem += new DrawItemEventHandler(cmb_Type_DrawItem);
    }

    void cmb_Type_DrawItem(object sender, DrawItemEventArgs e)
    {
        e.DrawBackground();
        string a = comboBox1.Items[e.Index].ToString();
        if (comboBox1.Items[e.Index].ToString().Substring(0, 1) == "-")
        {
            e.Graphics.DrawLine(Pens.Black, new Point(e.Bounds.Left, e.Bounds.Bottom - 1),
            new Point(e.Bounds.Right, e.Bounds.Bottom - 1));
            a = a.Substring(1, a.Length - 1);
        }            
        TextRenderer.DrawText(e.Graphics, a,
        comboBox1.Font, e.Bounds, comboBox1.ForeColor, TextFormatFlags.Left);
        e.DrawFocusRectangle();
    }

我需要的改进是在cmb_Type_DrawItem"中，我希望对comboBox1"进行参数化，因此当我调用它时，它可以应用于任何调用它的组合框(不仅仅是组合框1).

The improvement I need is in the "cmb_Type_DrawItem" i wanted the "comboBox1" to be parametrized so when i call it can be applied to any comboBox that called it (not just comboBox1).

推荐答案

使用 Martin 的解决方案加上一个公共变量.

Using Martin's solution plus a public variable.

    public Form1()
    {
        InitializeComponent();
        AttachHandler(comboBox1);
        AttachHandler(comboBox2);
        AttachHandler(comboBox3);
        AttachHandler(comboBox4);
        AttachHandler(comboBox5);
    }

    void AttachHandler(ComboBox combo)
    {
        combo.DrawMode = DrawMode.OwnerDrawFixed;
        combo.DrawItem += new DrawItemEventHandler(cmb_Type_DrawItem);
    }

    //using mycombo to make combobox variable
    void cmb_Type_DrawItem(object sender, DrawItemEventArgs e)
    {
        var mycombo = (ComboBox) sender;  // This is what I meant

        e.DrawBackground();
        string a = mycombo.Items[e.Index].ToString();
        if (mycombo.Items[e.Index].ToString().Substring(0, 1) == "-")
        {
            e.Graphics.DrawLine(Pens.Black, new Point(e.Bounds.Left, e.Bounds.Bottom - 1),
            new Point(e.Bounds.Right, e.Bounds.Bottom - 1));
            a = a.Substring(1, a.Length - 1);
        }
        TextRenderer.DrawText(e.Graphics, a, mycombo.Font, e.Bounds, mycombo.ForeColor, 
                     TextFormatFlags.Left);
        e.DrawFocusRectangle();
    }

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